SAP Message AJ036 - Reference base &1 for discount &2 is not permitted in the variant

Diagnosis
The variant you have specified requires a certain reference base fordiscounts. However, the corresponding discount has a differentreference base. Processing was canceled for this reason.
This constellation is caught in the billing master data and should nothave occurred.

Procedure
Check whether the correct discount was allocated to the discountoperand in the variant.
Report the error to SAP.